Securitization Activities - Additional Information (Details) - USD ($)	Aug. 31, 2017	Nov. 30, 2016
Transfers and Servicing [Abstract]
Carrying value of assets resulting from transfers	$ 11,000,000.0	$ 0
Carrying value of liabilities resulting from transfers	$ 11,000,000	$ 0

Carrying Value Of Liabilities Resulting From Transfers

No definition available.

Name:	jef_CarryingValueOfLiabilitiesResultingFromTransfers
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant